package layer

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/data"
	apierr "git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/errors"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer/frostfs"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer/tree"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/internal/logs"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"go.uber.org/zap"
)

const wildcard = "*"

var supportedMethods = map[string]struct{}{"GET": {}, "HEAD": {}, "POST": {}, "PUT": {}, "DELETE": {}}

func (n *Layer) PutBucketCORS(ctx context.Context, p *PutCORSParams) error {
	var (
		buf  bytes.Buffer
		tee  = io.TeeReader(p.Reader, &buf)
		cors = &data.CORSConfiguration{}
	)

	if err := p.NewDecoder(tee, p.UserAgent).Decode(cors); err != nil {
		return fmt.Errorf("xml decode cors: %w", err)
	}

	if cors.CORSRules == nil {
		return apierr.GetAPIError(apierr.ErrMalformedXML)
	}

	if err := checkCORS(cors); err != nil {
		return err
	}

	prm := frostfs.PrmObjectCreate{
		Payload:      &buf,
		Filepath:     p.BktInfo.CORSObjectName(),
		CreationTime: TimeNow(ctx),
	}

	var corsBkt *data.BucketInfo
	if n.corsCnrInfo == nil {
		corsBkt = p.BktInfo
		prm.CopiesNumber = p.CopiesNumbers
	} else {
		corsBkt = n.corsCnrInfo
		prm.PrmAuth.PrivateKey = &n.gateKey.PrivateKey
	}

	prm.Container = corsBkt.CID

	createdObj, err := n.objectPutAndHash(ctx, prm, corsBkt)
	if err != nil {
		return fmt.Errorf("put cors object: %w", err)
	}

	objsToDelete, err := n.treeService.PutBucketCORS(ctx, p.BktInfo, newAddress(corsBkt.CID, createdObj.ID))
	objToDeleteNotFound := errors.Is(err, tree.ErrNoNodeToRemove)
	if err != nil && !objToDeleteNotFound {
		return err
	}

	if !objToDeleteNotFound {
		for _, addr := range objsToDelete {
			n.deleteCORSObject(ctx, p.BktInfo, addr)
		}
	}

	n.cache.PutCORS(n.BearerOwner(ctx), p.BktInfo, cors)

	return nil
}

// deleteCORSObject removes object and logs in case of error.
func (n *Layer) deleteCORSObject(ctx context.Context, bktInfo *data.BucketInfo, addr oid.Address) {
	var prmAuth frostfs.PrmAuth
	corsBkt := bktInfo
	if !addr.Container().Equals(bktInfo.CID) && !addr.Container().Equals(cid.ID{}) {
		corsBkt = &data.BucketInfo{CID: addr.Container()}
		prmAuth.PrivateKey = &n.gateKey.PrivateKey
	}

	if err := n.objectDeleteWithAuth(ctx, corsBkt, addr.Object(), prmAuth); err != nil {
		n.reqLogger(ctx).Error(logs.CouldntDeleteCorsObject, zap.Error(err),
			zap.String("cnrID", corsBkt.CID.EncodeToString()),
			zap.String("objID", addr.Object().EncodeToString()))
	}
}

func (n *Layer) GetBucketCORS(ctx context.Context, bktInfo *data.BucketInfo) (*data.CORSConfiguration, error) {
	cors, err := n.getCORS(ctx, bktInfo)
	if err != nil {
		return nil, err
	}

	return cors, nil
}

func (n *Layer) DeleteBucketCORS(ctx context.Context, bktInfo *data.BucketInfo) error {
	objs, err := n.treeService.DeleteBucketCORS(ctx, bktInfo)
	objNotFound := errors.Is(err, tree.ErrNoNodeToRemove)
	if err != nil && !objNotFound {
		return err
	}

	if !objNotFound {
		for _, addr := range objs {
			n.deleteCORSObject(ctx, bktInfo, addr)
		}
	}

	n.cache.DeleteCORS(bktInfo)

	return nil
}

func checkCORS(cors *data.CORSConfiguration) error {
	for _, r := range cors.CORSRules {
		for _, m := range r.AllowedMethods {
			if _, ok := supportedMethods[m]; !ok {
				return apierr.GetAPIErrorWithError(apierr.ErrCORSUnsupportedMethod, fmt.Errorf("unsupported method is %s", m))
			}
		}
		for _, h := range r.ExposeHeaders {
			if h == wildcard {
				return apierr.GetAPIError(apierr.ErrCORSWildcardExposeHeaders)
			}
		}
	}
	return nil
}